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25 September 1995 <br /> AGE-NC Project No 95-0125 <br /> Page 4 of 5 <br /> between MW-8 and lAW-6 The overall north-northwest trend is consistent with the regional ground <br /> twater flow in the area <br /> 4 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> Petroleum hydrocarbons were detected in two of ten monitoring wells during this sampling event <br /> TPH-g was detected in MW-2 and MW-6 at concentrations of 5,400 and 440 pg/l (parts per billion <br /> ppb), BTE&X were detected m MW-2 and MW-6 at concentrations up to 610 ppb (toluene, MW-2) <br /> The analytical results of the ground water samples are summarized in Table 2 The laboratory report <br /> and chain-of-custody are presented as Appendix B <br /> 4 3 ANALYTICAL RESULTS OF SOIL AND GRAB WATER SAMPLES <br /> TPH-g was detected in soil sample from probing P3 collected at a depth of seven feet (P3-7) at a <br /> concentration of 3,200 ppm The same was found to contain TPH-d at 1,200 ppm Toluene, ethyl <br /> benzene and xylenes were detected also in this sample at concentrations of 9 2, 30 and 120 ppm, <br /> rrespectively Petroleum hydrocarbons were not detected in other soil samples analyzed nor in the grab <br /> ground water sample from probing P5 Analytical results of soil and grab ground water samples are <br /> summarized in Table 3 The laboratory report and chain-of-custody are included in Appendix C <br /> 5.0. CONCLUSIONS AND RECOMMENDATIONS <br /> 5 1 HYDROCARBON-E\dPACTED GROUND WATER <br /> Based on the detection of TPH-g in samples collected from MW-2 and MW-6, the current extent of <br /> dissolved petroleum hydrocarbons in ground water appears to be limited to a relatively small area <br /> near those wells(Figure 4) Except for minor variations, these two wells have historically shown the <br /> most consistent detection of dissolved hydrocarbons <br /> Due to elevated hydrocarbon concentrations in those wells, currently and in the past, it appears that <br /> a considerable volume of gasoline-impacted soils is present at the capillary fringe If an in-situ <br /> remediation method is selected to address the problem, a combination vapor extraction and air <br />' sparging system appears to be the most feasible method The method will address the soil and ground <br /> water contamination <br /> The next quarterly monitoring should be scheduled for late October 1995 <br />